How can we improve Microsoft Azure Logic Apps?

Can we get an ability to have simple code expressions in Logic Apps?

Question on the logic apps expression language:

One of the things that really can be a showstopper for logic apps, is the fact that the language is really limited. Just taking an example here. An API app would return a list of objects that include a datetime.
Then I want to loop through all the items and only send information out if that date is on a week-day. This can be done by an expression, but the expression language does not allow me to use custom code and does not have an implementation for this specific function. (and there are much more of those functions I can think of).

I obviously don't want to write a DateTime Api App, as that would be total overkill (and expensive at execution time).

Is there some plan to have .NET expressions in Logic Apps as well (something like: @userDefined(System.String.Format())). Or is there another option (assuming I cannot change the API app I'm using) one can think of?